CHAPTER XXVI. 



FERNS (FILICINEyE). 

 {The polypody, or Christmas fern.) 



255. Importance of study of ferns. — In taking up the study 

 of the ferns we find plants which are very beautiful objects of 

 nature and thus have always attracted the interest of those who 

 love the beauties of nature. But they are also very interesting 

 to the student, because of certain remarkable peculiarities of 

 the structure of the fruit bodies, and especially because of the 

 intermediate position which they occupy within the plant king- 

 dom, representing in the two phases of their development the 

 primitive type of plant life on the one hand, and on the other 

 the modern type. We will begin our study of the ferns by tak- 

 ing that form which is the more prominent, the fern plant itself. 



256. Selection of fern for study. — There are several ferns 

 which answer equally well for study. It is important to have 

 the entire plant, underground stem, roots, and leaves, and what 

 is of especial importance, some of the leaves should have the 

 "fruit dots." The common polypody (Polypodium vulgare) 

 is widely distributed, and will be useful for the practical study, 

 even though the Christmas fern here is used to illustrate the 

 descriptive part. There should, however, be no necessity for 

 limiting the study to a certain species, since in one locality 

 one species can be more easily obtained, while in another 

 locality another species may be more convenient to study. 



Exercise 52. 



257. The fern plant. — Take entire plants, if the common polypody, note 

 the creeping stem (root-stock or rhizome), the numerous brown scales cov- 



155 



